openssl: accept moving write buffer for write_nonblock

By setting the SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER flag.
This flag was introduced at the same time as
SSL_MODE_ENABLE_PARTIAL_WRITE in OpenSSL 0.9.4 and makes usage
with non-blocking sockets much easier.

Before this, a Rubyist would need to remember the exact object
which failed to write and reuse it later when the socket became
writable again.  This causes problems when the buffer is given
by another layer of the application (e.g. a buffer is given
by a Rack middleware or application to a Rack web server).

* ext/openssl/ossl_ssl.c (ossl_sslctx_s_alloc):
  enable SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER by default
  [Bug #12126]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@54466 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,9 @@
+Fri Apr  1 04:50:44 2016  Eric Wong  <e@80x24.org>
+
+	* ext/openssl/ossl_ssl.c (ossl_sslctx_s_alloc):
+	  enable SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER by default
+	  [Bug #12126]
+
 Fri Apr  1 01:13:55 2016  Benoit Daloze  <eregontp@gmail.com>
 
 	* thread.c (update_coverage): Do not track coverage in loaded files

ext/openssl/ossl_ssl.c

@@ -145,7 +145,8 @@ static VALUE
 ossl_sslctx_s_alloc(VALUE klass)
 {
     SSL_CTX *ctx;
-    long mode = SSL_MODE_ENABLE_PARTIAL_WRITE;
+    long mode = SSL_MODE_ENABLE_PARTIAL_WRITE |
+	SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER;
     VALUE obj;
 
 #ifdef SSL_MODE_RELEASE_BUFFERS

test/openssl/test_pair.rb

@@ -280,6 +280,35 @@ module OpenSSL::TestPairM
     }
   end
 
+  def test_write_nonblock_retry
+    ssl_pair {|s1, s2|
+      # fill up a socket so we hit EAGAIN
+      written = String.new
+      n = 0
+      buf = 'a' * 11
+      case ret = s1.write_nonblock(buf, exception: false)
+      when :wait_readable then break
+      when :wait_writable then break
+      when Integer
+        written << buf
+        n += ret
+        exp = buf.bytesize
+        if ret != exp
+          buf = buf.byteslice(ret, exp - ret)
+        end
+      end while true
+      assert_kind_of Symbol, ret
+
+      # make more space for subsequent write:
+      readed = s2.read(n)
+      assert_equal written, readed
+
+      # this fails if SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER is missing:
+      buf2 = Marshal.load(Marshal.dump(buf))
+      assert_kind_of Integer, s1.write_nonblock(buf2, exception: false)
+    }
+  end
+
   def tcp_pair
     host = "127.0.0.1"
     serv = TCPServer.new(host, 0)